
Proceedings Paper
LSST telescope primary/tertiary mirror hardpointsFormat | Member Price | Non-Member Price |
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Paper Abstract
The Large Synoptic Survey Telescope (LSST) utilizes an 8.4-meter cast borosilicate primary/tertiary mirror (M1M3).
This mirror system has stringent vibration and stiffness requirements because the LSST optical system does not include a
fast steering mirror and the mission requires a short slew and settling time. The position stability of the M1M3 relative to
the mirror cell is controlled by six displacement controlled actuators (subsequently referred to as "hardpoints") that form
a large hexapod. This design is based largely on previous hardpoints implemented for borosilicate mirror positioning.
Traditionally, all dynamic forces applied to these mirrors are reacted through their hardpoints. Consequently, the
characteristics of these hardpoints critically affect the ability of the telescope to meet the stringent dynamic requirements
without overstressing the mirror. The hardpoints must have a high stiffness of 120 N/um in the axial direction, while
protecting the mirror by limiting the loads in all six degrees of freedom. The non-axial direction loads are limited by
flexures. The axial loads are limited by a pneumatic breakaway mechanism. Since the hardpoints react the dynamic
mirror loads, the axial breakaway force may limit the telescope's slewing accelerations. The travel of the breakaway
mechanism must accommodate the transfer of the mirror from its active supports to its static supports. The hardpoint
positioning mechanism must have sufficient travel and resolution to properly position the mirror relative to the mirror
cell. Fulfilling these functions also requires numerous sensors, including a precision axial load cell which is paramount
in determining the figure control actuator forces.
Paper Details
Date Published: 21 July 2010
PDF: 12 pages
Proc. SPIE 7739, Modern Technologies in Space- and Ground-based Telescopes and Instrumentation, 77391J (21 July 2010); doi: 10.1117/12.857473
Published in SPIE Proceedings Vol. 7739:
Modern Technologies in Space- and Ground-based Telescopes and Instrumentation
Eli Atad-Ettedgui; Dietrich Lemke, Editor(s)
PDF: 12 pages
Proc. SPIE 7739, Modern Technologies in Space- and Ground-based Telescopes and Instrumentation, 77391J (21 July 2010); doi: 10.1117/12.857473
Show Author Affiliations
Joe DeVries, National Optical Astronomy Observatory (United States)
Douglas Neill, National Optical Astronomy Observatory (United States)
Douglas Neill, National Optical Astronomy Observatory (United States)
Ed Hileman, National Optical Astronomy Observatory (United States)
Published in SPIE Proceedings Vol. 7739:
Modern Technologies in Space- and Ground-based Telescopes and Instrumentation
Eli Atad-Ettedgui; Dietrich Lemke, Editor(s)
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